Thermally constructed stable Zn-doped NiCoOx-z alloy structures on stainless steel mesh for efficient hydrogen production via overall hydrazine splitting in alkaline electrolyte

• Published in: Journal of colloid and interface science 2023-06, Vol.640, p.737-749
• Main Authors: Kashale, Anil Ashok, Rasal, Akash Sanjay, Hsu, Fei-Chien, Chen, ChangChun, Kulkarni, Sayali Nitin, Chang, Chun Hao, Chang, Jia-Yaw, Lai, Yuekun, Chen, I-Wen Peter
• Format: Article
• Language: English
• Subjects: Hydrazine Oxidation Reaction; Hydrogen Evolution Reaction; Oxygen Evolution Reaction; Oxygen-Deficient Materials; Zinc Doping
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2023.02.142

The development of efficient and cost-effective electrocatalysts for hydrogen evolution is a need of time. Because hydrogen is superior to other natural energy sources owing to its high energy density of 120 to 140 MJ kg−1. Therefore, scientists have been working on a low oxidation potential needed hydrazine oxidation technique to produce hydrogen in place of the slow oxygen evolution mechanism. Direct hydrazine fuel cells (DHFCs) are promising as portable or vehicular power sources; nonetheless, they need the development of low-cost, efficient anodic hydrazine oxidation catalysts (HzOR). Herein, we have prepared zinc-doped oxygen-deficient nickel cobalt oxide (Zn-NiCoOx-z) alloy nanoarray on stainless steel mesh (SSM) using a hydrothermal method followed by thermal reduction treatment. The overall hydrazine splitting potential (OHzS) required to achieve 50 mA cm−2 in a two-electrode system (Zn-NiCoOx-z/SSM(-)∥Zn-NiCoOx-z/SSM(+)) is only 0.700 V, which is much less than the required potential for overall water splitting (OWS). [Display omitted] Hydrogen has a high energy density of approximately 120 to 140 MJ kg−1, which is very high compared to other natural energy sources. However, hydrogen generation through electrocatalytic water splitting is a high electricity consumption process due to the sluggish oxygen evolution reaction (OER). As a result, hydrogen generation through hydrazine-assisted water electrolysis has recently been intensively investigated. The hydrazine electrolysis process requires a low potential compared to the water electrolysis process. Despite this, the utilization of direct hydrazine fuel cells (DHFCs) as portable or vehicle power sources necessitates the development of inexpensive and effective anodic hydrazine oxidation catalysts. Here, we prepared oxygen-deficient zinc-doped nickel cobalt oxide (Zn-NiCoOx-z) alloy nanoarrays on stainless steel mesh (SSM) using a hydrothermal synthesis method followed by thermal treatment. Furthermore, the prepared thin films were used as electrocatalysts, and the OER and hydrazine oxidation reaction (HzOR) activities were investigated in three- and two-electrode systems. In a three-electrode system, Zn-NiCoOx-z/SSM HzOR requires −0.116 V (vs RHE) potential to achieve a 50 mA cm−2 current density, which is dramatically lower than the OER potential (1.493 V vs RHE). In a two-electrode system (Zn-NiCoOx-z/SSM(-)∥Zn-NiCoOx-z/SSM(+)), the overall hydrazine splitting potential (OHzS) required to reach